Retroreflective materials are employed for various safety and decorative purposes. Particularly, these materials are useful at night time when visibility is important under low light conditions. With perfect retroreflective materials, light rays are reflected essentially towards a light source in a substantially parallel path along an axis of retroreflectivity.
Many types of retroreflective material exist for various purposes. These retroreflective materials can be used as reflective tapes and patches for clothing, such as vests and belts. Also, retroreflective materials can be used on posts, barrels, traffic cone collars, highway signs, warning reflectors, etc. Retroreflective material can be comprised of arrays of randomly oriented micron diameter spheres or close packed cube-corner (prismatic) arrays.
Cube-corner or prismatic retroreflectors are described in U.S. Pat. No. 3,712,706, issued to Stamm on Jan. 23, 1973, the teachings of which are incorporated by reference herein. Generally, the prisms are made by forming a master negative die on a flat surface of a metal plate or other suitable material. To form the cube-corners, three series of parallel equidistance intersecting V-shaped grooves 60 degrees apart are inscribed in the flat plate. The die is then used to process the desired cube-corner array into a rigid flat plastic surface.
Further details concerning the structures and operation of cube-corner microprisms can be found in U.S. Pat. No. 3,684,348, issued to Rowland on Aug. 15, 1972, the teachings of which are incorporated by reference herein. A method for making retroreflective sheeting is also disclosed in U.S. Pat. No. 3,689,346, issued to Rowland on Sep. 5, 1972, the teachings of which are incorporated by reference herein. The disclosed method is for forming cube-corner microprisms in a cooperatively configured mold. The prisms are bonded to sheeting which is applied thereover to provide a composite structure in which the cube-corner formations project from one surface of the sheeting.
The present invention is directed to a xe2x80x9csee-throughxe2x80x9d retroreflective structure and a method for forming the same. The see-through retroreflective structure includes a transparent polymeric film, an array of retroreflective elements attached to the polymeric film, and an array of apertures through the retroreflective structure within the array of retroreflective elements. In one embodiment, the retroreflective structure includes a metalized reflective layer formed on the retroreflective elements and a support layer, such as a fabric, is attached to the metalized reflective layer. The see-through feature of the structure allows a person inside a vehicle or building to see out a window while those viewing outside can see a graphic display on the structure during the day and night.
A retroreflective structure is also provided which includes a film having a first side and a second side, a first array of retroreflective cube-corner elements attached to the first side of the film, and an array of apertures through the retroreflective structure within the array of retroreflective cube-corner elements. A second array of retroreflective cube-corner elements is attached to the second side of the film. The apertures can be formed by removing a portion of the film and the elements.
The method includes attaching an array of retroreflective elements on a transparent polymeric film. The array of retroreflective elements and the transparent polymeric film are perforated through the retroreflective structure to form an array of apertures, thereby forming a see-through retroreflective structure. In one embodiment, a metalized reflective layer can be applied to the retroreflective elements and a support layer, such as a fabric, is attached to the metalized reflective layer.
A retroreflective particle is further provided comprising a film having a first side and a second side, a first array of retroreflective cube-corner elements attached to the first side of the film, and a second array of retroreflective cube-corner elements attached to the second side of the film.
A transflector is also provided which includes a film, an array of retroreflective cube-corner elements attached to a first side of the film, an array of apertures through the retroreflective structure within the array of retroreflective cube-corner elements, and a printed sheet attached to a second side of the film. In one embodiment, the apertures are formed by removing a portion of the film and the elements. A diffuse film can be attached to the metalized reflective layer.
The present invention can be used as trim on clothing apparel, such as running suits and running shoes. In particular, the invention can display a moirxc3xa9 pattern. Also, the invention can be used on windows to partially retroreflect incoming light while allowing a person to partially see through the window from the other side. Further, the invention can be used as advertising display panels on windows, as reflective sun screens for windows in automobiles, etc. Furthermore, the structure is suitable for ink jet and digital printing with a whiteness background.